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91.
92.
Despite the publication of a number of papers dealing with the effect of drying on the soil labile P pool, less attention has been paid to the possible drying‐evoked changes in the more stable P pools. We applied Hedley's sequential fractionation procedure that aims at quantifying soil P reserves according to their decreasing plant availability to examine the effects of drying on soil P fractions in clayey soil samples of different cultivation history. To further investigate the contribution of organic matter disruption to the solubility of soil P, the P extracted in each fractionation step was divided into two size classes by filtering the suspension through a 0.2 μm membrane filter. There were no air‐drying‐induced changes in the total amount of P extracted in each fractionation step. However, air‐drying changed the distribution of water‐extractable P in size fractions; increase in the small‐sized P took place at the expense of large‐sized P. Air‐drying increased also small‐sized molybdate‐unreactive P (MUP) in the NaOH fraction giving evidence that drying‐induced alterations take place also in less labile P forms. The results revealed that air‐drying alters the extractability and distribution of P in various pools rather than the total amount of extracted P and that a large proportion of H2O‐ and NaOH‐extractable large‐sized MUP may remain undetected if only filtered samples are analyzed. 相似文献
93.
Genetic variation of isolated Picea balfouriana populations from the southeast of the Qinghai-Tibet Plateau 总被引:1,自引:0,他引:1
Zhuoxuan Lu Yuhua Wang Xiaolu Zhang Helena Korpelainen Chunyang Li 《Annals of Forest Science》2009,66(6):607-607
94.
The effects of temperature on anatomical and chemical characteristics of Quercus cerris cork were examined. Cork samples were subjected to isothermal air heating between 150 °C and 400 °C and analyzed for mass loss, cellular structure and chemical composition.The thermal decomposition of Q. cerris cork is similar to that of Q. suber cork. Cork is thermally stable below 200 °C and after that degradation depended on temperature and heating time with increasing mass loss, i.e. 3% at 200 °C 10 min and 46% at 350 °C 60 min. With temperature and starting at 200 °C, cells expanded, cell wall thickness was reduced and corrugations were lost.Extractives degraded at lower temperatures, although aliphatic extractives were found to be more stable. Suberin from Q. cerris was more heat resistant than Q. suber suberin, while lignin showed similar resistance.These results provide a basis for studies on the production of Q. cerris bark expanded cork agglomerates for insulation purposes. 相似文献
95.
96.
Helena Olczak-Woltman Małgorzata Schollenberger Wiesław Mądry Katarzyna Niemirowicz-Szczytt 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(3):385-393
Increased occurrence of cucumber angular leaf spot, Pseudomonas syringae pv. lachrymans, has caused significant losses in cucumber, Cucumis sativus, yield in Poland in recent years. These losses necessitated evaluation of the level of resistance in cucumber cultivars of
mainly Polish breeding, cultivated in Eastern Europe, and initiation of a breeding programme for resistance to this disease.
Screening for resistance was performed on 84 cucumber accessions under growth chamber conditions using a highly aggressive
strain of P. syringae pv. lachrymans. Most of the screened accessions were either susceptible or displayed intermediate resistance. The screening resulted in
the identification of five F1 hybrid cultivars moderately resistant to angular leaf spot. The identified F1 hybrids were self-pollinated up to the F4 generation. Individuals resistant to angular leaf spot were identified. These individuals can be used as a source of resistance
to angular leaf spot in future breeding efforts. 相似文献
97.
A previously reported procedure for the introduction of Borrelia spirochetes into tick larvae by immersion in a suspension of spirochetes was tested on Ixodes ricinus (L.) ticks and three of the most medically important European Borrelia genomic species, B. burgdorferi sensu stricto, B. garinii and B. afzelii. The procedure was compared with "classical" infection of nymphs by feeding on infected mice. Both methods yielded comparable results (infection rate 44-65%) with the exception of B. afzelii, which produced better results using the immersion method (44%) compared with feeding on infected mice (16%). Nymphs infected by the immersion method at the larval stage were able to transmit the infection to na?ve mice as shown by serology and PCR detection of spirochetal DNA in organs. The immersion method is faster than feeding on infected mice and provides more reproducible conditions for infection. It can be exploited for studies on both pathogen transmission and Borrelia-vector interactions. 相似文献
98.
Linnea J. Hansson John Koestel Eva Ring Annemieke I. Gärdenäs 《Scandinavian Journal of Forest Research》2018,33(2):166-177
Due to the great year-round demand for forest products, off-road forestry traffic occurs even when the ground is susceptible to soil compaction and rutting. We investigated the impacts of repeated passes with a laden forwarder (34?Mg) on the soil physical properties of two clear-cuts on stony till soils in northern Sweden. Core samples (n?=?71) were collected from the top 5?cm of mineral soil in and beside wheel tracks, after six passes with the forwarder. Soil physical properties were quantified using classical soil physical analyses and X-ray tomography. The hydraulic conductivity was 70% lower in the wheel tracks than in the soil beside. The X-ray image analysis indicated that this was due to the smaller total volume and lower connectivity of structural pores (φ?>?60?µm). Total porosity was 24% and 12% lower in the tracks at the two sites respectively, and mean bulk density was 1.39?g?cm?3 in the tracks, compared to 1.13?g?cm?3 beside them. To conclude, traffic changed the soil physical properties in a way that may lead to longer periods of high water content in the wheel tracks, increased risk of surface runoff and insufficient aeration for optimal seedling growth. 相似文献
99.
Aline Pissinatti Patricia Helena Santoro 《Communications in Soil Science and Plant Analysis》2018,49(13):1660-1670
The aim of this experiment was to test on-farm growing after composting the mixture of following legume plants Crotalaria juncea, Cajanus cajan, Mucuna aterrima with the grass Sorghum bicolor. The treatments were compared to commercial growing medium (CGM) and CGM+NPK to produce bedding plants of lettuce, broccoli, kale, and cabbage. The nutrient contents in CGM and CGM+NPK were higher than the values found in the mixture of the legumes plants with the grass. The pH was higher in the growing media from legume plants as well as the electrical conductivity in the combination CroSor and CajSor. The water retention capacity was higher in the treatments MucSor and CGM. The chemical attributes indicated that CroSor, CajSor, MucSor and CGM+NPK were better than CGM. The growing media from the mixture of legume with grass are an affordable alternative to produce bedding plants of lettuce, broccoli, kale and cabbage under organic agriculture system. 相似文献
100.
The influence of Ringer's lactate or HES 130/0.4 administration on the integrity of the small intestinal mucosa in a pig hemorrhagic shock model under general anesthesia 下载免费PDF全文